Re: Syscall changes registers beyond %eax, on linux-i386

From: Richard B. Johnson (
Date: Mon Sep 23 2002 - 08:11:20 EST

On Sun, 22 Sep 2002, Pavel Machek wrote:

> Hi!
> > It's a problem with a 'general purpose' compiler that wants to
> > be "all things" to all people. If somebody made a gcc-compatible
> > compiler, tuned to the ix86 characteristics, I think we could
> > cut the extra instructions by at least 1/2, maybe more.
> Remember pgcc?
> And btw cutting instructions by 1/2might look nice but unless you can
> keep it as fast as it was, its useless.
> Pavel
> --
Yes, but to see the affect of cutting down the instruction length, you
need to make benchmarks that emulate running 'forever'. Many bench-
marks access some memory over-and-over again in a loop. This does
not exercise the need to refill prefetch so the benchmarks ignore
the advantages obtained by reducing the amount of instructions needed
to be fetched from memory.

Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
The US military has given us many words, FUBAR, SNAFU, now ENRON.
Yes, top management were graduates of West Point and Annapolis.

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